In SQL Server Management Studio, in Object Explorer, right-click your database name and select Tasks -> Backup. The dialog that comes up gives you options on back up type, location of backup and all other kinds of stuff.

You can also do backups using T-SQL Scripts. If you are curios, after you have made the changes, click the script button on the top left of the dialog. That will generate a script for you. You don't have to do this - you can do the back up just by using that dialog.

You can also take periodic log backups to avoid having to take the full backup. Then you will be able to use a full backup together with the log backups to restore to the point in time of the last log backup.

Hi James,Thank you for your quick reply. So you suggest to take full database backup once and then periodic log backups, and in case of recovery I need to restore the full backup and then log backups. what about the changes made in between my last log backup and the DB failure? will there be online logs ? to recover the DB upto the point of failure?

I don't think you can achieve that reliably with just a single server and backups alone. You would need to use some technology such as transactional replication, database mirroring, or failover clustering. Paul Randal's white paper here is a great resource: http://msdn.microsoft.com/en-us/library/ee523927(v=sql.100).aspx He also has couple of video tutorials on the same topic.